A known touch sensor may have a structure including sensor electrodes formed on a transparent resin or glass substrate by patterning an ITO (indium tin oxide) layer, or may have a structure including sensor electrodes formed on a transparent substrate, as above, by patterning an electroconductive polymer. The former structure is highly transparent, but undesirably tends to increase cost. The latter structure is, on the other hand, advantageous for forming the electrode pattern more inexpensively than the case of the ITO layer because the latter structure allows the electrode pattern to be printed. Unfortunately, printing the electrode pattern does not allow a finer electrode pattern to be formed as desired without limitation. In addition, since electroconductive polymers are less transparent than ITO, the electrode pattern of an electroconductive polymer has a contrast to the outside thereof. This is a cause of what is called “see-through ribs”, a phenomenon where the boundary of the electrode pattern can be seen.
For example, Japanese Unexamined Patent Application Publication No. 2010-105588 discloses a measure against such a see-through phenomenon for using an electroconductive polymer. In this disclosure, an insulating coating film having substantially the same color and substantially the same transmittance as an electroconductive coating film of a sensor electrode is formed around the electroconductive coating film, thereby reducing the visibility of the electrode pattern.
Japanese Unexamined Patent Application Publication No. 2012-32923 discloses the technique of forming dummy electrodes in the spaces between patterned electrodes. Since the dummy electrodes are formed on the same surface as the sensor electrodes, this technique enables the dummy electrodes and the sensor electrodes to be formed at one time and is thus efficient.